Rhubarb Custard Bars – The Perfect Sweet Tart Dessert for All Seasons

Name: Rhubarb Custard Bars
Prep time: 15 min
Cook time: 45 min
Total time: 1 h
Yield: 12 servings
Cuisine: American
Ingredients: 1 1/2 cups all-purpose flour (for crust); 1/2 cup powdered sugar; 3/4 cup cold unsalted butter, cubed; 2 cups chopped rhubarb; 1 1/2 cups granulated sugar; 1/4 cup all-purpose flour (for filling); 3 large eggs; 1/4 tsp salt; 1 tsp vanilla extract; 1 cup heavy cream

Posted on May 26, 2025

Homemade rhubarb custard bars with a golden crust and creamy filling on a plate

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Rhubarb custard bars are one of those desserts that just make you feel good. They’re creamy, tangy, sweet, and full of comfort in every bite. If you’ve never had one, think buttery crust on the bottom, smooth custard in the middle, and a layer of tart rhubarb that ties it all together.

These bars are the kind of treat you make when you want something easy but impressive. Whether it’s for a backyard hangout or a quiet evening in, rhubarb custard bars always hit the spot. In this guide, I’ll share everything you need to know to make them, store them, freeze them, and even add your own twist.

Let’s get started and bake something amazing together

Rhubarb custard bars served on a plate with a rustic kitchen background

Table of Contents

PART 1: What Are Rhubarb Custard Bars?

Rhubarb custard bars are one of those desserts that instantly feel familiar, even if it’s your first time trying them. At their core, they’re made with three simple layers that work perfectly together—a buttery shortbread crust, a creamy custard center, and a top layer of chopped rhubarb that bakes down into soft, tangy goodness. It’s a flavor combo that hits just the right note between sweet and tart.

What makes rhubarb custard bars so special is how unpretentious they are. You don’t need any fancy ingredients or complicated steps to make them. The crust comes together quickly, the custard gets whisked until smooth, and the rhubarb gets tossed on top like it’s no big deal. But once you take a bite, you’ll see why these bars are often the first thing to disappear at family gatherings and spring bake sales.

Rhubarb itself has been used in desserts for generations. It’s one of those seasonal ingredients that shows up just as the weather starts to warm up, making these bars a spring and summer favorite. People love them not just for the taste, but for the nostalgia. They remind you of gardens, sunshine, and old-fashioned kitchens where baking was more about love than perfection.

So if you’re looking for a dessert that’s simple, crowd-pleasing, and full of flavor, rhubarb custard bars are exactly what you need. And once you’ve made them once, you’ll find yourself coming back to this recipe every time rhubarb season rolls around.

PART 2: Ingredients for Perfect Rhubarb Custard Bars

When it comes to baking rhubarb custard bars, you don’t need anything fancy—just a few pantry staples and fresh rhubarb. That’s part of what makes this recipe so loved. It’s simple, approachable, and still packed with flavor. But even with a short ingredient list, the details matter. The right balance of textures and sweetness is what makes these bars truly shine.

Here’s a breakdown of what you’ll need to make the best rhubarb custard bars:

The crust

The foundation of any great bar is the crust, and here it’s all about buttery shortbread. You’ll need:

All-purpose flour
Powdered sugar
Cold unsalted butter, cubed

This mix creates a crumbly, golden base that holds everything together and adds just the right amount of richness without overpowering the filling.

The custard filling

Now for the star of the show—the custard. This creamy middle layer is what gives the bars that luscious, smooth texture. You’ll need:

Large eggs
Granulated sugar
All-purpose flour
A pinch of salt
Vanilla extract
Heavy cream or milk

It comes together quickly and bakes into a silky layer that pairs beautifully with tart rhubarb.

The rhubarb layer

Fresh chopped rhubarb is the highlight here. It softens as it bakes, releasing a tangy burst that cuts through the sweet custard. If fresh rhubarb isn’t available, frozen works too—just be sure to thaw and drain it well to avoid extra moisture in the bars.

Want to try something fun? Swap out half of the rhubarb for chopped strawberries or raspberries. It adds another layer of flavor and a pop of color without changing the texture too much.

Ingredient swaps and dietary options

If you’re looking for a gluten-free option, simply use a 1:1 gluten-free flour blend for both the crust and custard. Dairy-free? Try using coconut cream instead of heavy cream and a plant-based butter for the crust. The bars might be slightly softer, but still delicious.

Getting the ingredients right is the first step to perfect rhubarb custard bars. The good news is, most of these items are probably already in your kitchen, and if not, they’re easy to grab from any local store.

Close-up of a freshly baked rhubarb custard bar showing layered crust, custard, and rhubarb

PART 3: Step-by-Step Rhubarb Custard Bars Recipe

Making rhubarb custard bars is easier than it looks. Even if you’re not a confident baker, this recipe walks you through each step with no stress. All you need is a little prep, a good pan, and some patience while everything bakes and cools.

Here’s a simple breakdown so you can get that perfect blend of buttery crust, creamy custard, and tangy rhubarb every time.

Step 1: Prep your tools and ingredients

Before you get started, gather everything you need. Preheat your oven to 350°F and line a 9×13-inch baking dish with parchment paper, leaving some overhang to help lift the bars out later. This trick makes cutting and serving so much easier.

Have your rhubarb chopped and ready, along with separate bowls for mixing the crust and the filling.

Step 2: Make the crust

In a large bowl, whisk together flour and powdered sugar. Add in cold, cubed butter and use your hands or a pastry cutter to blend until it looks like coarse crumbs.

Press the crust mixture evenly into the bottom of your pan and bake for 15 to 20 minutes, or until the edges are just golden. While that’s baking, move on to the filling.

Step 3: Mix the custard

In a clean bowl, whisk together eggs, sugar, flour, salt, vanilla extract, and heavy cream until smooth and creamy. The goal is a pourable custard—don’t overmix or you’ll get bubbles in the final texture.

Fold in the chopped rhubarb gently so it’s evenly coated.

Step 4: Layer and bake

Once the crust has baked slightly and cooled for a few minutes, pour the rhubarb custard filling right on top. Use a spatula to spread it out evenly if needed.

Return the pan to the oven and bake for 35 to 45 minutes. You’ll know it’s ready when the edges are golden and the center is set but still has a slight jiggle.

Step 5: Cool, chill, and serve

Let the bars cool completely on a wire rack. For the cleanest cuts, chill the pan in the fridge for at least an hour before slicing.

Lift the bars out using the parchment overhang, then cut into squares. Dust with powdered sugar or add a dollop of whipped cream if you want to make them extra pretty.

That’s it. With just a few easy steps, your homemade rhubarb custard bars are ready to enjoy. They’re sweet, tangy, smooth, and always a crowd favorite.

Must-Have Kitchen Tools for Rhubarb Custard Bars

To make the process easier and cleaner, having the right tools on hand can make a big difference. Here’s what you’ll need:

9×13-inch baking dish – The perfect size to give your bars that nice thickness
Parchment paper – Helps with easy removal and cleaner cuts
Mixing bowls – At least two: one for crust, one for filling
Whisk – For creating a smooth, lump-free custard
Measuring cups and spoons – Precision is key when baking
Pastry cutter or fork – To blend butter into the crust mixture
Spatula – Great for spreading the custard evenly and scraping down bowls
Wire cooling rack – Helps the bars cool evenly after baking
Sharp knife – For cutting clean, even squares once the bars are set

Having these kitchen basics will help your rhubarb custard bars turn out just right with less mess and more ease.

PART 4: Best Tips for Baking Rhubarb Custard Bars Like a Pro

Want to make sure your rhubarb custard bars turn out perfect every time? These classic tips will help you avoid common mistakes and get that ideal blend of buttery crust, creamy filling, and tender rhubarb.

1. Use fresh rhubarb when you can

Fresh rhubarb delivers the best texture and a brighter flavor.
If using frozen rhubarb, make sure to thaw completely and drain off excess liquid to avoid a watery custard.

2. Chill before slicing

Let the bars cool completely after baking.
Then refrigerate for at least 1 hour before cutting to help the custard set and make cleaner slices.

3. Don’t overmix the custard

Whisk your filling just until smooth.
Overmixing adds too much air and can cause bubbles or cracks during baking.

4. Watch the baking time

Bake until the edges are golden and the center is just set with a slight jiggle.
Overbaking can result in a tough texture or cracked top.

5. Line your pan with parchment

Use parchment paper with an overhang on the sides of the pan.
This makes it easy to lift the bars out in one piece and slice without sticking.

6. Adjust sweetness to taste

Rhubarb is naturally tart, and the sweetness can vary.
Taste your rhubarb or filling and add up to ¼ cup more sugar if needed.
Want a sharper bite? You can even cut the sugar slightly for more tang.

7. Use the right pan

A 9×13-inch metal baking dish works best for even heat distribution.
Avoid glass if possible—it retains heat and may lead to overbaking.

With these simple, classic baking tips, your rhubarb custard bars will be everything they should be—soft, creamy, tangy, and melt-in-your-mouth delicious.

PART 5: Storage and Shelf Life of Rhubarb Custard Bars

Once you’ve baked a pan of rich, tangy rhubarb custard bars, the next question is how to store them so they stay fresh and delicious. Like most custard-based desserts, these bars need a little care when it comes to storage—but it’s super simple once you know what to do.

How to store them properly

After baking, allow the bars to cool completely at room temperature.
Once cooled, transfer them to an airtight container or keep them in the baking pan, tightly covered with plastic wrap or foil.
Always store rhubarb custard bars in the refrigerator due to their custard filling.
Stored this way, they will stay fresh for up to 3 days.

Tips for serving after storing

Serve straight from the fridge for a firmer texture.
If you prefer a softer bite, let them sit at room temperature for 15 to 20 minutes before serving.
You can dust with fresh powdered sugar or add whipped cream just before serving if desired.

Can they be frozen for later?

Yes, rhubarb custard bars freeze well when handled correctly.
For best results, cut them into individual bars first, wrap each one tightly in plastic wrap, and place them in a freezer-safe container or zip bag.
Frozen bars will keep for up to 2 months.
When you’re ready to enjoy, thaw them in the refrigerator overnight or let them sit at room temperature for about an hour.

Storing these bars the right way means you can enjoy their creamy, tangy goodness for days—or even weeks—after baking. They’re a dessert that travels well, saves well, and still tastes amazing every time you come back for more.

PART 6: Creative Variations and Twists on the Classic

Once you’ve made rhubarb custard bars the classic way, it’s hard not to start thinking about all the ways you can make them your own. The base recipe is so simple that it’s perfect for playing around. Whether you want to add a little sweetness, a fun topping, or adjust it for different diets, there are tons of easy ways to switch things up.

Mix in strawberries

Strawberries and rhubarb are best friends. Try swapping in half strawberries and half rhubarb for a slightly sweeter version that still has that signature tang. It also adds a pop of color and looks super pretty when sliced.

Add a crumb topping

Want some crunch on top? Mix a quick crumble with oats, brown sugar, chopped nuts, and butter. Sprinkle it on before baking, and you’ll get a delicious contrast to the creamy custard. It feels a bit like a pie-bar hybrid—in the best way.

Brighten it up with lemon

Adding a little lemon zest to the custard is an easy trick for more flavor. It gives everything a fresh, bright vibe that pairs perfectly with the rhubarb. Just a teaspoon goes a long way.

Make mini versions

If you’re baking for a party or want something easy to share, try pressing the crust into a muffin tin and making mini rhubarb custard bars. They’re cute, perfectly portioned, and bake a little faster too.

Go creamy with a cheesecake layer

For something extra rich, you can add a thin layer of sweetened cream cheese between the crust and custard. It’s kind of like cheesecake meets rhubarb bar—and it totally works.

Try a gluten-free or dairy-free version

Need to adjust the recipe?

Use a gluten-free flour blend for the crust and custard
Swap in coconut cream and plant-based butter to make it dairy-free
These simple swaps keep the bars just as tasty and friendly for more people at the table.

Add warm spices

If you like a cozy twist, sprinkle a little cinnamon or nutmeg into the custard. It gives the bars a hint of warmth—especially nice if you’re making them in cooler weather.

There’s really no wrong way to make rhubarb custard bars. Once you know the basics, you can tweak the recipe to fit your mood, what’s in your fridge, or who you’re baking for. That’s what makes them so much fun.

Can you freeze rhubarb custard bars?

Yes, you totally can. Just make sure the bars are completely cool before freezing. Cut them into squares, wrap each one in plastic wrap, and pop them into a freezer-safe bag or container. They’ll keep for up to 2 months. When you’re ready to enjoy, just let them thaw in the fridge or on the counter for about an hour. They’re just as tasty chilled.

Where should I store leftover rhubarb custard bars?

The fridge is your best bet. Because these bars have a custard filling, they need to stay chilled. Keep them in an airtight container or cover the baking pan with foil or plastic wrap. They’ll stay fresh for about 3 days. You can eat them cold, or let them sit out for 15 minutes to soften up a bit.